Mucins are glycoconjugated proteins which are secreted by vesicles and discharged on the surface of the conjunctival epithelium of the eye. Mucins are found on moist, mucosal epithelia, and are thought to combine mechanical protection of eye tissue as well as chemical and immune protection of mucosal tissue. The surface of the eye is kept moist and lubricated by tear film. Mucins anchor this tear film to the epithelium and protect the eye surface from bacterial, chemical and physical invasion of foreign bodies.
U.S. Pat. Nos. 6,348,508 (Denick, Jr. et al.), 2004/0063620 (Xia et al.), and 2004/0063591 (Borazjani et al.) disclose compositions for treating dry eye or for treating contact lenses that comprise a cationic polysaccharide. In the case of eye drop solutions, the cationic polysaccharides, after binding to the mucosal eye tissue, may in turn promote the mucins in the eye, either by supplementing the mucin and/or by helping to bind and maintain mucin on the eye surface.
In the case of contact lenses, mucins are often viewed as a debris that, like other proteins, should not accumulate on the contact lens surface. For example, U.S. Pat. No. 5,985,629 (Aaslyng et al.) discloses contact lens cleaning and disinfecting compositions comprising an enzyme and an enzyme inhibitor. Aryl boronic acids are mentioned as a possible enzyme inhibitor and/or disinfectant, but the purpose of the compositions is to remove soil deposits from a contact lens, such soil deposits including mucin (at column 1). As another example, U.S. Pat. No. 6,649,722 (Rosenzweig et al.) discloses contact lens compositions. At column 28, it is reported that binding of mucin to the lens was at a desirably low enough level that the mucin would not lead to corneal adhesion of the lens.